The inventors of this invention have developed the following apparatus for molding a mold:
The apparatus is comprised of an upper and a lower molding space, an aeration mechanism to discharge foundry sand into the molding spaces, and a squeezing mechanism to squeeze the foundry sand,
wherein the upper and the lower molding space are defined by an upper and a lower flask each having intakes disposed at their side walls for foundry sand, a match plate disposed between the upper and the lower flask, and the squeezing mechanism having squeeze plates, which can be inserted in openings of the upper and the lower flask having no match plate. After filling the upper and the lower molding space with the foundry sand through the intakes of the upper and the lower flask by the aeration mechanism, the squeezing mechanism squeezes the foundry sand in the upper and the lower molding space by causing the upper and the lower squeeze plates to further approach each other. (See patent documents 1 and 2.)
However, the hardness and the strength near the inner surface that corresponds to the match plate, of the upper and the lower mold that are made by using the apparatus explained above, are not high enough.
Patent document 1: Japanese Patent Laid-open Publication No. H06-277800
Patent document 2: Japanese Patent Laid-open Publication No. S59-024552